1. Field of the Invention
The present invention relates to a device for mapping in vivo electrical activity in a heart.
2. Description of the Prior Art
Devices for mapping electrical activity in a patient's heart are known which include an imaging unit for generating an anatomical reference image of a patient's heart, an electrode catheter with at least one electrode for sensing intracardiac electrical activity for insertion into the heart, and signal processing equipment for determining activation times, from sensed electrical activity, in relation to a reference time for electrical activity at different points in the heart, and for generating a graphic image showing the activation times at different points in the heart and superimposing this graphic image onto the anatomical image.
One general problem in this type of electrophysiological studies is to correlate information measured in time to the anatomical structure of the heart. For this purpose, a common method is to apply a transparent film to a fluoroscope monitor, to "freeze" the image for every time sample, and to manually enter time data at the position of the electrode catheter's tip on the monitor. The tip of the catheter is then moved to a new position, and the procedure is repeated until an isochronous image is obtained.
Time data, e.g. in the form of activation times in relation to a reference time at different points in heart tissue, can be translated into colors in order to achieve color-coded representation of time information.
A device of the initially described type is previously known from U.S. Pat. No. 5,433,198 which describes a system for such cardiomapping, whereby received information is utilized for treating tachycardia with ablation. Thus, the system according to this patent has an imaging unit which, via a detector, generates an anatomical image of the heart on a monitor. The imaging unit is fluoroscopic or ultrasonic. With multi-electrode catheters connected to appropriate signal processing equipment, a real-time image is generated of arrival times of a characteristic signal at different points in the heart with respect to a reference time and local isochronous images are displayed on the monitor, from which the origin of a tachycardia can be identified.